The present disclosure relates to a hinge structure suitably used for a copying machine, a printer, a scanner and others having a document cover and an image forming apparatus including the hinge structure.
In an image forming apparatus, an auto document feeder (ADF) for ejecting documents that is automatically fed on a platen glass (a document rack) and is subject to an image forming processing is provided. The auto document feeder is openably/closably supported by a hinge structure with respect to a platen glass, and includes a document cover for pressing documents on the platen glass when the hinge structure is closed.
This conventional type of hinge structure is configured such that an attachment member protruded in the document cover is insertably/removably provided in an attachment recessed part formed on an upper surface of the apparatus main body. In addition, in the image forming apparatus including this type of hinge structure, when documents are pressed onto the platen glass by the document cover in order to read out a thick document such as a book or when the auto document feeder is detached in order to carry out a periodical maintenance work, the attachment member is configured to be lifted upwardly along the attachment recessed part. However, in this case, in a case where a heavy load is applied to the hinge structure, particularly, there is a risk that the attachment member is not smoothly lifted up and is strongly rubbed with the attachment recessed part, and consequently defects such as break or deformation of the hinge structure may be generated.
Accordingly, in order to the foregoing problems, for example, an image forming apparatus including a hinge structure in which rollers are attached to upper and lower parts of the attachment member (a hinge foot) and a protrusion for prevention of retaining in a lower part of the attachment member has been proposed.
However, in the hinge structure described above, when the attachment member is lifted upwardly along the attachment recessed part and the upper roller is detached from the attachment recessed part, the attachment member is fallen forward to pry the attachment recessed part, and consequently the attachment member is sometimes not smoothly lifted up. In addition, in a case where a thicker document than defined limited thickness is pressed by the document cover through a user's carelessness, there is a risk that defects such as break or deformation of the hinge structure may be generated.